Injury to and/or diseases of the spine frequently result in damage to or abnormalities in the vertebrae, the intervertebral discs, the facet joints and to the connective tissue and ligaments around the spine. Such damage or abnormalities may result in spinal instability causing misalignment of the vertebral column and wear of the intervertebral discs and vertebral bony surfaces, a chronic and progressive deterioration which typically results in severe pain, loss or restriction of motion, and eventually, loss of mobility of the individual suffering from the condition.
One treatment option for addressing spinal disorders is via surgical intervention and the placement of fusion, stabilization and/or repair devices on or adjacent to the spine or between adjacent vertebrae. Certain surgical procedures are irreversible, for example, fusion techniques using bone grafts or synthetic implants to fuse vertebra, and may also significantly alter vertebral range of motion. Other procedures, for example procedures for installing spinal implants or pedicle screw systems for fixating two or more vertebrae, are intricate, time consuming and highly invasive. Alternative solutions include the insertion of interspinous or intra-laminar spacers in the space between adjacent vertebrae to control relative motion between and to stabilize the two vertebrae. However, the stabilization does not extend above or below the insertion point, leaving the remaining portions of the spinal column subject to unstable motion and the potential damage resulting therefrom.
Various prior art systems have attempted to address the problems described above. U.S. Pat. No. 5,645,599 issued to Samani on Jul. 8, 1997 (the '599 patent), discloses an interspinal implant device having a generally u-shaped, spring-like configuration for insertion between the spinal processes of adjacent vertebrae. Samani's device includes opposing pairs of upwardly and downwardly extending brackets adapted to be secured to the spinal process, thereby providing for flexible positioning of the adjacent vertebrae. However, the apparatus of the '599 patent does not attribute to the overall stability of the spinal column; its effect being limited to the two specific vertebrae to which it is attached. It is also difficult to attach multiple devices configured in accordance with Samani's disclosure at adjacent segments due to interference of the bracket portions.
Hochschuler et al disclose various intra-laminar stabilization systems in U.S. Patent Application Publication No. US 2009/0204150 published on Aug. 13, 2009 (the '150 publication), and in U.S. Patent Application Publication No. US 2011/0106163 published on May 5, 2011 (the '163 publication). The '150 publication discloses a pair of oppositely disposed hook members that are translationally positioned on a rod and adapted to engage the laminar regions of adjacent vertebra and maintain a preselected spacing there between. However, the apparatus of the '150 publication does not stabilize other vertebrae in the spinal column, its effect being limited to the two adjacent vertebrae which it engages.
The Hochschuler et al. '163 publication discloses an interlaminar stabilizing system which includes a structure adapted to be disposed between two adjacent vertebrae as described above with respect to the apparatus of the '150 publication. The '163 structure further includes a support structure which is secured to the second vertebra to further restrict the interval spacing between the adjacent vertebrae. However, the system of the '163 disclosure also does not stabilize the vertebrae in the remaining portions of the spinal column for the reasons set forth above.
Moreover, none of the known prior art systems address the problem of “transition syndrome” or “adjacent segment disease” associated with fusion of adjacent vertebrae. In fusion, if a motion segment is eliminated via fusion, the unfused adjacent segments above and below the fused vertebrae take up and bear the additional forces induced by bending and rotational movement of the spine, which may result in so-called “transition syndrome” over the long term. In addition, none of the prior art systems provide for augmenting previously installed spinal hardware to enhance stability, adjust intervertebral distraction, and so forth.
Accordingly, a need exists for an improved spinal stabilization system which provides both flexibility and stability to the spinal column and which addresses the combination of problems not solved by the prior art.